Short-wavelength transverse collective modes in a metallic glass

The atomic dynamics of the metallic glass Mg 70 Zr 30 and the same sample after crystallisation was investigated at room temperature using neutron inelastic scattering techniques. For the first time the dispersion of short-wavelength collective density excitations could be measured in the glassy metal for a few momentum transfers near the first maximum of the static structure factor. From the intensity distribution in the spectra the authors conclude that the modes observed are transverse collective density excitations in the glassy system (transverse phonons in the polycrystal). They compare their findings with molecular dynamics and analytical calculations on the same system.